This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Ribonuclease MRP (RNase MRP) is a site-specific endoribonuclease involved in metabolism of various RNA molecules including rRNA. RNase MRP is a ribonucleoprotein complex which contains a large RNA molecule and a number of protein components. The RNA moiety of RNase MRP is presumed be responsible for catalysis, while the role of the protein components is not clear. The major problem that hinders further understanding of this enzyme is the absence of available high-resolution structural information. At this moment, there are no reported structures of any part of RNase MRP. Our research is aimed at obtaining high-resolution structural information on the individual components or subcomplexes and, eventually, the holoenzyme of RNase MRP. Recently, we have established that two of the protein components of RNase MRP, Pop6 and Pop7, form a heterodimer which binds the RNA component of RNase MRP. We produced crystals of this triple complex containing Pop6, Pop7 and their binding site on RNA. We will solve the crystal structure of this complex to shed light on the RNA-protein interactions in this important class of catalytic ribonucleoprotein complexes. The structure will reveal the interplay between protein and RNA molecules in this important class of RNA-based enzymes.